rich running can also be caused by vacuum leaks ~ the computer will add extra fuel to compensate for the extra air caused from the vacuum leak sucking in extra air...
rich running can also be caused by vacuum leaks ~ the computer will add extra fuel to compensate for the extra air caused from the vacuum leak sucking in extra air...
He did say he'd been checking for vacuum leaks with starting fluid, so I discounted that. Still, it's never a bad idea to *carefully* replace vacuum hoses when they're this old. Be extra careful on plastic or other non-metallic vacuum hose barbs as they tend to get brittle and break easily.Originally Posted by xboxrox
It's the other way around; a vacuum leak introduces "false air" (more air than the ECU is aware of) to the intake charge, so it injects less fuel than necessary for the actual air present, causing a lean misfire that would show up as high HC with low CO in exhaust gas analysis, whereas a rich condition would show high HC with high CO -- i.e., the exhaust would be "rich" but only because of unburned fuel due to the misfire, rather than too much fuel quenching efficient combustion.
BTW, IIRC '90 had a one-year-only FI system that was replaced for '91-on, which complicates troubleshooting and parts availability.
1987 Dodge Ram 50 4G54 RWD longbed ("Elmo")
1979 Lancia Beta Zagato spider ("Lola")
1982 Lancia Beta Zagato spider ("Luigi")
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